# # 例2-1
# import numpy as np
# arr1=np.array([1,2,3])
# print('一维数组arr1:\n',arr1)
# arr2=np.array((4.5,5.6,6.8),dtype='int32')
# print('一维数组arr2:\n',arr2)
# arr3=np.array([[1,2,3],[4,5,6]],dtype='float32')
# print('2*3的二维数组arr3:\n',arr3)
#
#
# import numpy as np
# arr11=np.array([1.1,2.2,3.3])
# print('一维数组arr11:\n',arr11)
# arr111=np.array((-1,-2,-3),dtype='int32')
# print('一维数组arr111:\n',arr111)
# arr1111=np.array([3,-2,2.3],dtype='float32')
# print('一维数组arr1111:\n',arr1111)

# 例2-2
import numpy as np
arr1=np.zeros(2)
print('一维数组arr1:\n',arr1)
arr2=np.zeros((2,3))
print('二维数组arr2:\n',arr2)
arr3=np.ones((3))
print('二维数组arr3:\n',arr3)
arr4=np.ones((3,3))
print('二维数组arr4:\n',arr4)
arr5=np.empty((4))
print('二维数组arr5:\n',arr5)
arr6=np.empty((3,4),dtype='int')
print('二维整型数组arr6:\n',arr6)

arr7=np.ones((2,3))*5
print('二维数组:\n',arr7)